Silver halide photosensitive materials are processed by development, fixing and water washing, for example, after being subjected to an imagewise exposure.
In recent years, a demand has arisen for minimizing the hazardous components in effluent streams and reducing the amount of effluent, or providing a system with no effluent. In particular, from the viewpoints of environmental protection and conservation of resources, a demand has arisen for a reduction in the amount of washing water. Various studies have been conducted in response to these demands.
As a result, in JP-A-58-105150 (the term "JP-A" as used herein signifies an "unexamined published Japanese patent application") a photographic processing apparatus is disclosed in which the washing water is reused with the aid of a reverse osmotic pressure device. Photographic processing apparatus is furnished with a reverse osmotic pressure device in which the liquid intake, the concentrate side outlet and the diluted side output are connected to the water washing tank, the bleach-fixing tank and the water washing tank, respectively. The washing water expelled from the water washing tank is treated by means of the reverse osmotic pressure device, and the concentrate which is produced is returned to the bleach-fixing tank while the dilute liquid is returned to the water washing tank.
Furthermore, JP-A-60-241053 proposes a method of processing in which silver halide color photosensitive materials are color developed, processed in a processing bath which has a fixing capacity and then subjected to a stabilizing process substantially without water washing wherein the stabilizer liquid is treated by means of a reverse osmosis membrane. With this method of processing, the production of yellow staining on long term storage and the development of staining immediately after processing are said to be prevented.
Moreover, for reducing the replenishment rate of
the washing water, JP-A-62-254151 proposes a method of processing silver halide color photosensitive materials in which, when water washing and/or stabilization is carried out using a multi-stage counter-flow system after treating a silver halide color photosensitive material in a bath which has a fixing ability, the overflow from the water washing tank, and/or stabilizing tank is introduced into a storage tank and the liquid in the storage tank is treated with a reverse osmosis membrane. The liquid permeating through the reverse osmosis membrane is returned to the water washing tank and/or the stabilizing tank, and the concentrated liquid is returned to the storage tank in order to reduce the amount of concentrated liquid which is expelled from the reverse osmosis membrane treatment apparatus.
The reverse osmosis membrane treatment of washing water and stabilizing liquid is very useful for economizing on washing water and stabilizer liquid, but the main problem with this method is that the amount of liquid permeated is reduced by blockage of the membrane. Although the efficiency is initially high with reverse osmosis membrane treatment, the membrane will inevitably become blocked in a short period of time.
As a result of analyzing this problem, it has been discovered that blockage of the fine pores of the membrane results from the attachment of trace quantities of silver sulfide which are produced in the washing water or stabilizing liquid and of colonies of bacteria to the membrane surface.
This phenomenon is especially pronounced when the rate of replenishment of the bath which has a fixing ability is reduced, the silver concentration in the bath which has a fixing ability is increased and the amount of silver which is introduced into the water washing tank or stabilizing tank is increased with an increase in the amount of silver sulfide formed in the washing water or stabilizing liquid. When the replenishment rate of the washing water or stabilizing liquid is reduced, the residence time of the washing water or stabilizing liquid in the tank is increased, promoting an increase in the amount of silver sulfide which is produced. Moreover, it has also been confirmed that in those cases where the color development bath contains benzyl alcohol, the benzyl alcohol is carried over into the washing water or stabilizing bath, where it promotes the growth of bacteria and increases the amount of material which is attached to the membrane.